pareser error while sending data as json to php script using jquery ajax

I'm sending some data to my sever at localhost using jquery's $.ajax.

The data is JSON object.

as follows:

javascript

var jso={
    "data": {
        "Game_name": "Road Rash",
        "cheat": "xyzzyspoon!",
        "effects": [
            {
                "nitro": true
            },
            {
                "chain": false
            }
        ]
    }
};
function sendData(){
var queryString=JSON.stringify(jso);
$.ajax({
    type: "POST",
    url: "/gamers_cheats.php",
    contentType: "application/json; charset=utf-8",
    traditional: true,
    dataType: 'json',
    data: queryString,
    success: function(data){
        console.log(data);
    },
    error: function(data,textStatus,jqXHR){
    alert("Unknown Error occured :- \n "+textStatus+"\n error");
    console.log("Unknown Error occured :- \n "+textStatus+"\n error");
    }
});
}
sendData();

and handling data in my php file as:

gamers_cheats.php:

<?php
var_dump($_POST);
echo"\n Count:- ".count($_POST);
// This is Just a demo file
?>

But the problem is $.ajax alerts the error: part with textStatus as parsererror. Also same is happening even if I didn't use JSON.stringify.

and if The lines:

    contentType: "application/json; charset=utf-8",
    traditional: true,
    dataType: 'json',

were removed then the request is sent to the sever but that isn't a valid request as it adds extra slashes (\) to every (") in JSON object.

like:

\"data\": {
        \"Game_name\": \"Road Rash\",
        \"cheat\": \"xyzzyspoon!\",
        \"effects\": [
            {
                \"nitro\": true
            },
            {
                \"chain\": false
            }
        ]
    }

So that gives error while processing it on server side. Is there any way to properly send POST JSON data using jquery ajax and to properly handle it on server?

and one more question, can i add extra $_POST parameters which are not in JSON format to my queryString as data: queryString +"&&navigator="+navigator.userAgent+"" ? but that also ain't working (This is not important though, Just curious about it).

FYI I'm running IIS 7 server with php 5.2 and JQuery version 1.7.2 with JSON2.js .

Hope experts here will help me.